Design Methodology for the Selection of Temporary Erosion and Sediment Control Practices Based on Regional Hydrological Conditions

Abstract

Construction-related activities typically disturb established vegetation, resulting in the potential for accelerated erosion. Because of the associated water quality impacts of construction activities, the USEPA has established regulatory programs to manage stormwater runoff emanating from construction sites. Currently, designers typically rely on “rules of thumb” for the design and selection of temporary erosion and sediment control practices. To provide a hydrologically sound approach, this research developed a quick and direct sizing method based on Technical Release–55 methodology. The analysis focused on Type-II and Type-III rainfall distributions, with 171 hydrological simulations performed. The results yielded applicable equations for the determination of flow rates representative of regional conditions for a typical 0.405-ha (1.0-acre) roadway median drainage basin. Geographical information system (GIS) analyses were used to develop and analyze regional hydrological characteristics. The GIS modeling results showed the average 2-year, 24-h rainfall depth and soil curve number for newly graded developing urban areas in the state of Alabama to be 11.3 cm (4.43 in.) and 88.5, respectively. Multiple linear regressions were performed on simulated data to develop equations to calculate expected total storm volume, peak flow rate, and average flows for 30-, 60-, and 90-min peak volumes based on regional input rainfall parameters and a weighted curve number. The developed relationships reported low standard errors when compared with a complete hydrologic analysis. Designers can implement these regression relationships as design aids in selecting and sizing appropriate runoff control practices for projects under consideration when developing stormwater pollution prevention plans.